Center-feed nozzle in a contained cylindrical feed-inlet tube for improved fluid-energy mill grinding efficiency

Abstract

This invention relates to a supersonic center-feed nozzle system within the feed-inlet tube of a fluid-energy mill used for grinding particulate material such as titanium dioxide. Particularly, in the feed-inlet tube of the present invention, particulate material is introduced into the supersonic feed jet of primary grinding fluid in almost a perpendicular fashion, with the supersonic nozzle installed in the center of the particulate material core, imparting momentum to the particulate material. The momentum entrains the particulate into the main grinding chamber of the feed-inlet tube. In the main grinding chamber of the feed-inlet tube, a secondary stream of grinding fluid, introduced annularly, constricts the primary jet's divergent flow, enabling a higher turbulent mixing of the grinding fluids and the particulate material.

1. A center feed nozzle system comprising:
 a) a L-shaped feed inlet comprising a first and a second end; a wall surrounding a hollow interior comprising a central axis, 
 b) the wall comprising
 i) an exterior surface, 
 ii) an interior surface, 
 iii) an annular inlet consisting of a hollow interior beginning on the exterior surface and extending at an angle from about 90° to about 165° through the wall to the interior surface forming one annular opening; and 
 iv) a jet nozzle; 
 wherein the jet nozzle and the annular inlet are positioned on the wall so that the jet nozzle produces a flow to the central axis and the annular inlet is located downstream of the flow. 
 
 
     
     
       2. A process for reducing the size of particulate comprising:
 1) supplying particulate material to a center-feed nozzle system, wherein the center-feed nozzle system comprises:
 a) a L-shaped feed inlet comprising a first and a second end; a wall surrounding a hollow interior comprising a central axis, 
 b) the wall comprising
 i) an exterior surface, 
 ii) an interior surface, 
 iii) an annular inlet consisting of a hollow interior beginning on the exterior surface and extending at an angle from about 90° to about 165° through the wall to the interior surface forming one annular opening, and 
 iv) a jet nozzle; 
 
 wherein the jet nozzle and the annular inlet are positioned on the wall so that the jet nozzle produces a flow to the central axis and the annular inlet is located downstream of the flow; 
 
 2) supplying a first grinding fluid to the jet nozzle; 
 3) supplying a second grinding fluid to the annular inlet 
 4) supplying the particulate material, the first grinding fluid, and the second grinding fluid from the center feed nozzle system into a grinding chamber of a fluid energy mill. 
 
     
     
       3. The process of  claim 2 , wherein the first and the second grinding fluids flow at a velocity of from about 0.5 Mach to about 7 Mach. 
     
     
       4. The process of  claim 2 , wherein the particulate material comprises titanium dioxide. 
     
     
       5. The process of  claim 2 , wherein the first and the second grinding fluids each comprise a gaseous fluid selected from the group consisting of air, nitrogen, steam and a combination thereof. 
     
     
       6. The process of  claim 2 , wherein the first and/or the second grinding fluid(s) comprises steam.